Biology review! In Part 3 of our Equine Massage Primer, we’ll go over the organ systems shared by all mammalian organisms—that means you and your horse! Organ systems are the second-largest level of organization that comprise an organism (or “body”), and are in turn comprised of organs, which are made of tissues, which are collections of cells, comprised of molecules, made up of atoms. Phew! Let’s go macro again: back to organ systems.
The maintenance of homeostasis is a prerequisite for any organism’s ability to thrive. Each of the organ systems participates collaboratively in sustaining equilibrium. You’ll notice that many organ systems’ functions overlap; likewise, the benefits fostered by massage within each system are often shared across the board. In my mind, the somewhat arbitrary categorization of the organ systems only serves to emphasize the interdependence of all components of a well-functioning body, however they may be delineated. Though we can identify specific benefits of massage upon each system, let’s also appreciate a wider lens: massage, like the body’s systems themselves, supports not just parts, but the whole.
Equine Organ Systems: Components, Functions, and Response to Massage
1. Integumentary system
The integumentary system is comprised of your horse’s skin, hair, hooves, and sweat glands. It is responsible for containing and protecting underlying tissue, acting as a barrier against foreign substances, and regulating body temperature, and serves as the primary sense organ. Massage aids in the maintenance of the skin’s elasticity and brings healthy oils to the surface of the coat while assisting in shedding dead cells. Massage communicates through sense receptors in the skin to aid in the release of naturally-occurring “happy” neurochemicals—endorphins, dopamine, oxytocin and serotonin—to allow whole-body relaxation and, in turn, healing.
2. Skeletal system
The skeletal system includes bones, joints, cartilage, and ligament. It provides structure, encloses and protects vital organs, and serves as an attachment site for connective tissue, which, in turn, enables movement. Bones also serve as a reserve storehouse for minerals, and the bone marrow found in larger bone structures is a site of hematopoeisis, or blood-cell production. Massage is famous for improving circulation, which nourishes skeletal cells. Through gentle range-of-motion exercises, joints are mobilized and lubricated through the circulation of synovial fluid. Skeletal alignment is passively improved by massage’s promotion of relaxation in contracted muscles.
3. Muscular system
The muscular system is comprised of muscles and tendons. Sometimes grouped with the skeletal system (as in the “musculoskeletal system”), the muscular system shares some of the skeletal system’s functions—namely, structure and movement. The muscular system also assists in thermoregulation by generating heat. It is massage’s effects on the muscular system that many of us are most familiar with: massage improves circulation to promote blood flow (or hyperemia) towards and within muscle tissue; it helps break down adhesions in contracted, overstretched, immobilized, and injured muscles, which restores mobility; it can aid in the relaxation of voluntary muscles.
4. Nervous system
The nervous system consists of the central nervous system (the brain and the spinal cord) and the peripheral nervous system (nerve receptors throughout the body). The nervous system is the control center of the body. It detects information about the environment and processes sensory input, initiates quick responses to stimulus, regulates all other body systems, and generally connects both conscious and subconscious will to action. Massage enhances biofeedback to give the brain more information about tension in the body. It has a normalizing effect on the autonomic (unconscious) nervous system, can affect the secretion of analgesic hormones to relieve pain, releases muscle spasms in tissue surrounding the spinal cord, and tones all components of the nervous system as of a result of improved circulation.
5. Endocrine system
The endocrine system includes the principal endocrine glands—the pituitary, adrenals, pancreas, pineal, gonads, thyroid, and parathyroid glands—as well as hormones and their production sites within most tissues of the body. The endocrine system is responsible for producing and secreting hormones throughout the body to regulate system-wide homeostasis over time. As opposed to the nervous system’s instant relay of information, the endocrine system is a slow-fuctioning mechanism that receives its signals and transports hormones through the blood. Therefore, massage’s enhancement of circulation serves the endocrine system well. Similarly, massage also passively aids the immune system, as some hormones produce lymphocytes that assist in systemic immunization.
6. Circulatory system
Also referred to as the cardiovascular system, the heart, blood, and vessels comprise this system. The heart propels the circulation of blood, which serves as a medium for the transport of oxygen, nutrients, waste, and hormones throughout the body and between tissues and organs. Once again, we see that massage reigns in the stimulation of circulation: by dilating blood vessels to reduce blood pressure, aiding the movement of venous fluid back towards the heart, and strengthening the contractions of the heart, massage enhances circulation in general, which, in turn, improves the efficiency of its role in substance exchange between cells.
7. Lymphatic system
The lymphatic (or immune) system is made up of white blood cells, lymph nodes, lymph vessels, bone marrow, and the thymus. Lymph is clear fluid mostly comprised of water and white blood cells; it is transported through lymph vessels and filtered through the nodes to return extracellular fluid to the bloodstream. The lymphatic system participates in the immune function of detecting and neutralizing or destroying foreign substances in the body. Massage supports these mechanisms by improving lymphatic circulation to reduce swelling, edema, and contusions. It also increases the number of red and white blood cell platelets, an important component of an efficient lymphatic system. In these ways, massage strengthens immunity to make the organism more resistant to illness, and to hasten convalescence if illness does occur.
8. Respiratory system
The respiratory system includes the nasal cavity, sinuses, trachea, the two bronchi and lungs, and the diaphragm. The respiratory system handles the exchange of gases—your horse inhales air, the respiratory process supplies the blood with oxygen, your horse’s exhalation excretes carbon dioxide and water back into the air, ad infinitum. Massage’s promotion of relaxation and the release of tension helps normalize your horse’s breathing pattern to foster the absorption of oxygen. Because of its effect on circulation, massage also helps flush waste from the lungs to further improve respiratory efficiency, which can improve athletic performance as a result.
9. Excretory systems (digestive & urinary)
The digestive system includes your horse’s oral cavity, esophagus, stomach, liver, small and large intestines, rectum, and anus; the urinary system includes the kidneys, ureters, urinary bladder, and urethra. The digestive system breaks food down into absorbable parts and eliminates the solid residue, while the urinary system eliminates remaining fluid and constantly regulates the balance between water and electrolyte content. Through its effects on the parasympathetic nervous system, massage can stimulate the secretion of digestive fluids as well as peristalsis (intestinal contraction), and may also relax tense or spastic abdominal and intestinal walls. Additionally, massage increases the excretion of fluid waste products (e.g. metabolized protein) while assisting in flushing fluids through the kidneys. Reduced blood pressure associated with the circulatory effects of massage also improves the action of the urinary system.
Note: traditionally, the reproductive system is included in lists of the mammalian organ system; however, the effects of massage therapy on equine reproduction have, to my knowledge, not been quantified and my remarks would be conjecture. Massage and the human reproductive system do enjoy ancient associations and are bolstered by the benefit of ample research. Let curiosity guide you!